Journal of Materials and Engineering Structures
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The effect of cool paints and surface properties of the facade on the thermal and energy efficiency of buildings in a hot and arid climate
Get PDFThe facade of a building is a decisive factor in the thermal and energy performance of buildings. Its surfaces are considered as zones of heat transfer between the inside and the outside. Surface properties, especially color and texture; which have an important role on solar absorption and thermal emittance of the facade and subsequently the thermal operation of the building. The purpose of this article is to study the impact of surface properties of the facade on the thermal comfort and energy efficiency of buildings in a hot and arid climate. The investigation is based on an experimental approach by taking measurements in test cells with an insulating paint (with nanoparticles) as well as on a numerical study by the dynamic thermal simulation software TRNSYS. Several parameters were studied such as ambient temperature, internal and external surface temperature and energy consumption. The results showed that the surfaces of the facade represent with excellence the place of heat exchange between interior and exterior whose surface properties have a colossal impact on the thermal and energy operation of the building. The insulating paint with its nanoparticles has a considerable impact on the reduction of temperature. The proper choice of material absorption has a great influence on the reduction of temperatures and energy requirements of the building
Evaluation of Fatigue Limit and Mechanism of Fatigue Crack Initiation of Epoxy Coatings used as Lining for Crude Oil Storage Tanks
Get PDFIn this paper, the fatigue performance of three types of epoxy coatings (pure, Novolac and reinforced by glass-flake) were studied in crude oils and air environments. A group of equipment is constructed in a laboratory and used in rotating bending fatigue tests of single and double layers of coats applied to ASTM A537-C1 steel. The results showed that the fatigue limit of A537 steel improved after coatings and that the fatigue limits of the coated and uncoated steel conducted in the crude oil solution was significantly lower than those obtained in the air environment. The results of the microscopic inspection indicate that there are three types of fatigue cracks initiation mechanism in steel coatings and environment affects the shape of fracture surface. In addition, the observation of the broken section of the single-layer test sample showed that it has more coat failure compared to the double layers coats
Analysis of static behavior of a P-FGM Beam
Get PDFIn this paper, the systematic arrangements are acquired to foresee the static behavior of the P-FGM beam and which have been gotten by Navier's solution. The numerical outcomes got by the new shear models are presented and compared with those available in the literature to see the influence of the geometry and the mixing law on the static behavior of this type of FGM beams
Fracture parameters formulation for single edge notched AS4 stitched warp-knit fabric composite plate
Get PDFThe three-dimensional problem of the fracture for the single edge notched tension plate (SENT) of orthotropic material is considered in this paper. The finite element solution is used to evaluate the singular and non-singular terms of the William series, i.e. Stress intensity factor (SIF) and T-stresses namely T11, T13 and T33. Based on the obtained numerical results, a fitting procedure is performed in order to propose analytical formulations giving the fracture parameters near the crack tip. The obtained results are in good agreement with the finite elements calculation and other literature results
Uniaxial tensile response of coconut coir fiber-reinforced polyethylene Composites
Get PDFThe roles of Composite materials in a variety of engineering applications have increased due to their enhanced strength and modulus, especially polymer-based composites which is one of the commercially available composites. The uniaxial tensile properties of polyethylene matrix reinforced with coconut coir fibers has been studied and the results from experiments and analytical models are presented. The compositional dependence of tensile strength, stiffness (elastic modulus), modulus of resilience and ductility are explored for different proportions of the constituent materials through experiments and analytical models. The results from experiments showed that the properties measured were greatly affected by the fiber mass fraction with optimized properties obtained at fiber content of 10 wt%
Deriving a specific response spectrum from the site of the Algiers Grand Mosque (Algeria)
Get PDFL’estimation de la réponse sismique en surface du sol peut être faite par plusieurs méthodes expérimentales, approchées et numériques. Cette étude consiste à utiliser la simulation numérique pour déterminer la réponse en surface en termes d’accélération maximale et spectre de réponse des profils de sol localisé au niveau du site de la mosquée d’Alger en tenant compte de la non-linéarité du comportement du sol, avec un comportement linéaire équivalent (dégradation hystérésis du module de cisaillement G). Les réponses calculées en surface qu’elles soient amplifiées ou dés-amplifiées par rapport à l’excitation à la base (séisme du 21 Mai 2003 à Boumerdès) nous indiquent la présence des effets de site et ce qui permet la dérivation d’un spectre de calcul spécifique au site étudié.The estimation of the soil seismic response at the surface can be made by several experimental methods, approximate and numerical. This study consists in using numerical simulation to determine the surface response in terms of maximum acceleration and response spectrum of soil profiles located at the site of the Grand Mosque of Algiers, taking into account the soil’s non-linearity behavior, with an equivalent linear behavior (hysteresis degradation of the shear modulus G). The responses calculated on the surface that they are amplified or de-amplified compared to the excitation at the base (earthquake of May 21, 2003 in Boumerdès) indicate the presence of the site effects and which allows the derivation of a spectrum calculation to the studied site
Etude expérimentale de l’effet du processus électro-osmotique dans un sol fin salin de la région de Mostaganem
Get PDFEn génie civil, l'électro-osmose est une technique utilisée comme moyen de déshydratation et de traitement des sols fins pour l’amélioration et la dépollution. Elle est aussi utilisée en agriculture pour la désalinisation des sols. Dans cette étude, l'effet de l’électro-osmose sur les propriétés d'un sol fin de la région d’Ain Nouissy-Mostaganem sous une différence de potentiel électrique a été analysée. L’objectif est d’étudier le comportement de l’écoulement hydrique et la modification de certains paramètres, tels que la conductivité électrique, le pH et les limites d’Atterberg durant et après le processus électrocinétique. Ces paramètres permettent de comprendre et de contrôler la performance de cette technique vis-à-vis du traitement considéré. Le chauffage du sol durant ce processus a été abordé à travers la température de surface, indiquant une perte d’énergie relative lorsque le gradient de tension dépasse une valeur optimale.In civil engineering, electro-osmosis is a technique used as a means of dehydration, treatment of fine soils for the improvement and remediation. It is also used in agriculture for the desalinization of soils. In this study, the effect of electro-osmosis on the properties of a fine soil of the Ain Nouissy-Mostaganem region under a difference of electric potential was analyzed. The objective is to study the behavior of the water flow and the modification of some parameters, such as the electrical conductivity, the pH and the Atterberg limits during and after the electrokinetic process. These parameters make it possible to understand and control the performance of this technique with respect to the treatment under consideration. Soil heating during this process was approached through the surface temperature, indicating a loss of relative energy when the voltage gradient exceeds an optimal value.En génie civil, l'électro-osmose est une technique utilisée comme moyen de déshydratation et de traitement des sols fins pour l’amélioration et la dépollution. Elle est aussi utilisée en agriculture pour la désalinisation des sols. Dans cette étude, l'effet de l’électro-osmose sur les propriétés d'un sol fin de la région d’Ain Nouissy-Mostaganem sous une différence de potentiel électrique a été analysée. L’objectif est d’étudier le comportement de l’écoulement hydrique et la modification de certains paramètres, tels que la conductivité électrique, le pH et les limites d’Atterberg durant et après le processus électrocinétique. Ces paramètres permettent de comprendre et de contrôler la performance de cette technique vis-à-vis du traitement considéré. Le chauffage du sol durant ce processus a été abordé à travers la température de surface, indiquant une perte d’énergie relative lorsque le gradient de tension dépasse une valeur optimale
The Influence of Deformability of Horizontal Diaphragms in the Distribution of Seismic Loads to Bracing Elements in Rectangular Buildings
Get PDFThe operations of a floor, as a significant structural element, have an influence on the stability of the structure when it acts as a horizontal diaphragm. In this study, the in-plane deformability of rectangular floors of single story buildings is examined under the effects of horizontal seismic actions. Therefore, the effects of parameters influencing the behavior of the floor such as size opening and their location, position of shear walls, span-to-depth ratio, and materials constituting the floor were studied. Results suggest that a diaphragm will behave in a flexible manner whether it is classified as rigid or flexible. However, a small opening in the floor can change the behavior of a diaphragm assumed rigid and make it behave like a flexible diaphragm. Additionally, flexible diaphragms can distribute horizontal seismic shear forces to vertical resisting elements due to the relative rigidity of the shear wall. These results are in contradiction with seismic codes such as ASCE/SEI 7-10 [1], FEMA 356 [2], and Eurocode 8[3], further the size of opening that make flexible diaphragm behave like rigid diaphragm was suggested by formula. For the building with a shear wall, the classification of the diaphragm in seismic codes such ASCE is not accurate enough and they need to reform with taking into consideration the location of the opening in the floor
Laboratory study on the effects of hydraulic and granulometric parameters on the response of granular soil to internal erosion
Get PDFErosion is a major environmental problem to agricultural land as well as to civil engineering infrastructures. Rainwater infiltration into granular soils can lead to the migration of fine particles by suffusion. This experimental study is conducted to evaluate the susceptibility to erosion of cohesionless soils. The soil under investigation was collected from the coastal region of Mostaganem (West of Algeria) where erosion has recently caused several damages. To assess soil instability to erosion, two approaches have been proposed in the literature: the geometric approach and the hydraulic approach. Few studies have examined the combination of the two methods. The objective of our study is the combination of the two approaches by determining the critical hydraulic load responsible for triggering erosion as a function of soil characteristics. An experimental parametric study was conducted to determine the influence of initial amount of fines, hydraulic gradient and axial stress on the initiation and evolution of suffusion. A combination of the interactions between these parameters allowed us to express the critical hydraulic gradient and to identify the hydraulic behavior of the soil according to the studied parameters. This approach can better estimate the erodibility of cohesionless soils. It can be used in future development studies at this site to reduce the risk of erosion
Numerical evaluation of shear strength of CFS shear wall panels for different height-to-width ratios
Get PDFThis paper presents a numerical evaluation of the shear strength of Cold Formed Steel Shear Wall Panels (CFS-SWPs) having 1.33:1 and 1:1 height-to-width aspect ratios with 0.76 mm steel plate sheathing thickness and 1:4, 1.33:1 and 1:1 height-to-width aspect ratios with 0.46 mm steel plate sheathing thickness, which are not provided by AISI S400. For this purpose, shell finite element (FE) models, validated with test results, are completed in ABAQUS v2018 with nonlinear geometry, material and connection. A good agreement is achieved between experimental and numerical results in terms of shear strength-lateral displacement and failure modes.It is concluded that, for a fixed height-to-width aspect ratio, the shear strength of SWPs having different screws spacing varying from 50.4 mm up to 152.4 can be assessed by interpolation using this FE method. However, by interloping the shear strength from 4:1 to 1:1 height-to-width aspect ratio, the shear strength can be underestimated; hence, it is more economical for practicing engineers to use the shear strength assessed by this proposed FE method for 1.33:1 and 1:1 height-to-width aspect ratios. Moreover, the effect of the sheathing thickness having 0.46 mm is evaluated and proposed as it lacks in data provided by the code (i.e., AISI S400)